August 21, 2017
On August 21, 2017, the moon's shadow will pass across the continental United States. (And nothing on earth can make it stop or deviate by so much as a centimetre from its path.) Only a thin strip of land, from Oregon to South Carolina, will be within the band of totality, the cone of darkness within which the disc of the moon is seen to obscure the whole of the sun in daytime. Darkness will fall. Stars will come out (if the weather is clear). Birds will perch and prepare to sleep. Dogs will fret.
While the buildup to this (the penumbra) will take an hour, with some remarkable phenomena, such as crescent-shaped shadows, the totality itself will last only 2 minutes 40 seconds maximum. Yet this is an event that people will come around the world to experience and everyone who sees it will remember for the rest of their lives.